Notched sheets are used, for example, for the production of stators for electric motors. During stamping of the sheets, burrs develop so that the stacked sheets catch on one another. Often the sheets are also annealed, and thus bake together on unclean surfaces. Finally, it is often the case that the stamped, and optionally annealed, sheets delivered for production of the stators are not entirely even. Under these circumstances, where the sheets are to be pushed off "flat" from the stack, the sheets engage the burrs of the notches formed therein and hook together or otherwise stick to one another.
Further difficulties are also encountered if a specific number of sheets forming a packet are to be removed from the stack at one time. In this regard, a specific stator requires a specific height or thickness of the sheet packet. Packet formation of sheets delivered in stacks is difficult because there are substantial tolerances for the individual sheets, and these tolerances can add up in the overall sheet packet. For example, there is a distinct difference in height of the sheet stack or packet on diametrically opposite sides of the sheet cut if the starting material of the sheet was slightly wedge-shaped in cross section and the sheets are stacked in the position corresponding to that assumed in the stamping process. In addition, there are variations and tolerances in thickness and height because of the stamping burrs and dirt between the sheets.
Prior art devices of the type under consideration do not adequately deal with the difficulties indicated above. German Pat. No. OS 26 56 705 describes a pusher apparatus including a pusher which is yieldingly and resiliently spring mounted in a wedge-shaped guide in the direction of thrust which causes the lowermost sheet of a stack to be pushed out laterally and flat. Thus, if the pusher encounters resistance of some kind, the pusher can move downward in the wedge-shaped guide. However, this apparatus does not prevent sheets from engaging each other in the area of the notches when the "pushing off" operation occurs and thus hanging up on one another.
German Pat. No. 20 19 924 shows a packet device in which a sheet packet of specific height is taken off from the upper end of a stack which, in order to improve the precision of the operation, is placed under pressure. At the height of the stack corresponding to the plane of separation, crossed blades press obliquely upward and downward against the side edges of the adjacent sheets which are to be separated. The clamping load of the blades on the individual sheets is partly relieved by the pressure on the entire stack. The separated sheet packet is then received and lifted off by a tensioning mandrel. It is a disadvantage of this device that the work cannot be performed continuously because as the sheet packet is lifted off in this upward direction, the remaining stack must be held stationary until the sheet packet is clear. Moreover, it has been shown that the separation of firmly baked together sheets by means of the blade edges pressing laterally against the sheets does not always work acceptably. In addition, because the sheets have the sides opposite the blades pressing against a fixed guide, the main force of the blades is passed through the sheets to the fixed guide. Thus, in order to attain separation of the sheets, the force of the blades must be relatively great and these forces can lead to deformation of sheets that have been weakened by notches. It also happens rather frequently that the sheet stack cannot be separated in the correct planes because at this point the sheets cling together very firmly instead of being seated only loosely on one another. In this connection, it is also noted that the tolerances of the first stamped inner notches of the sheets are smaller than at the periphery resulting in bowed sheets. Thus, the obliquely placed blades do not always come into contact with the correct sheet. It should also be noted that this device is not suitable for taking off individual sheets from the stack or for manually operated devices.